Could these Hyundai oil problems point to something common?

Start with the specifics, not the timing of when the cars were paid off. Write down each car’s model, engine, mileage, service dates, oil level checks, and what the shop found. Check each VIN with a Hyundai dealer for any applicable recalls or service campaigns, then ask whether the symptoms fit a known engine or oil-consumption problem.

Low oil can come from a leak or from the engine burning oil, and those call for different checks. Ask the mechanic to document the cause and keep the repair and maintenance records. The fact that there are three cars is worth investigating, but by itself it can’t show that a failure was planned.

I’d separate the three cases before calling them one pattern. A blown rod is a specific kind of engine failure, while low oil could mean a leak, oil consumption, or a service issue. Get the exact diagnosis for each car, ideally in writing, and compare the engines and mileage. If the cars share an engine, that makes a common technical issue more plausible, but it still needs evidence.

If an engine is still under warranty, contact the manufacturer or dealer before authorizing major work, and keep receipts for oil changes and any repairs. For an active leak or knocking noise, stop driving and have it checked rather than risking more damage.

For the car that’s still running, check the oil level regularly until the cause is clear, and note how much oil it uses and over how many miles. A mechanic can inspect for external leaks and test for oil consumption. If the explanation from the first shop is vague, a second opinion is reasonable.

Three cases in one family would make me ask questions too, but the useful next step is diagnosis and records, not assuming the failures were intentional.